**6. Conclusions and future perspectives**

Microorganisms in winemaking are as necessary as they are undesirable, depending on the strain and/or the time it proliferates. The growth of spoilage microorganisms in must and wine not only exerts a considerable influence on consumer acceptance, but can also lead to uncountable economic losses. Currently, the spoilage of wine by microorganisms is mainly controlled by applying SO2. However, due to the current global concern about the negative effects of SO2 on human health, the wine industry is facing the challenge of attempting to reduce or eliminate its use. Proposed chemical or physical alternatives are insufficient or/and non-feasible for implementation as microbial stabilization procedures in the wine industry.

Pulsed Electric Fields emerge as a thoroughly suitable alternative technique for the stabilization of must and wine, or as a technique combined with low doses of SO2 to ensure antioxidant protection. PEF efficacy has been studied against the main wine-related spoilage microorganisms along the different winemaking stages, but mostly under lab-scale or pilot plant conditions. Best results have been obtained when PEF was combined with mild treatment temperatures and/or with low concentrations of SO2, or with other preservatives. Furthermore, several studies have reported to have found no negative effects or changes in the sensory quality of wines treated with PEF.

PEF technology is currently being applied in a number of industrial food processing applications. Thus, the development and optimization of PEF devices and chambers is accelerating in order to adapt them to current demands while facilitating the industrial implementation of such new techniques to food. The devices' flexibility has been highly improved, along with different types of treatment chambers, depending on the type of matrix and on treatment conditions.

The International Organization of Vine and Wine (OIV) recently approved the application of PEF to grapes in order to enhance and reduce maceration time in winemaking [48]. The technology is currently being evaluated as a microbial stabilization and decontamination process. The OIV resolutions thus suggest that PEF is a gentle technology without negative consequences for must or wine, but offering interesting improvements in terms of their quality. The applicability of PEF in several other winemaking steps such as maceration or aging-on-lees, along with the current feasibility of scale-up potential, makes this procedure thoroughly attractive for future implementation as a highly versatile technology in the wine industry. Furthermore, the energetic requirements for must/wine PEF-optimized pasteurization can ranged from 20 to 200 kJ/kg. Thus, the power consumptions imply very low costs in comparison with the traditional techniques and the innovative ones suggested.

Generally, however, the ranges of PEF parameters studied for purposes of microbial decontamination (at laboratory scale), are still very intense in comparison with the ones used in grape electroporation (high-intensity voltages or long treatment times). Such intense conditions have certain drawbacks for implementation in wineries due to the power limitation of current PEF devices. This implies that PEF should be applied at very low flow rates, which are not feasible in winemaking on an industrial scale. The current challenge lies therefore in studying low and mild PEF conditions not investigated so far in-depth: PEF alone, or in combination with other methods. One of the most promising combinations is the application of PEF treatments in association with mild temperatures or/and with reduced doses of SO2. A reduced amount of studies have already proven the synergetic effect that emerges between these methods when applied in combination. Thus, in order to successfully implement PEF technology in wineries for purposes of microbial decontamination, it will be necessary to define the lowest-intensity PEF parameters which, combined with mild temperatures and reduced-SO2, have the highest synergetic effect. This would allow for a considerable increase in the processing capacity of PEF units, thereby facilitating this technique's industrial application in the wine industry without affecting sensory properties, while attending to widespread demands for the reduction of SO2.

*Microbial Decontamination by Pulsed Electric Fields (PEF) in Winemaking DOI: http://dx.doi.org/10.5772/intechopen.101112*
